A conventional resettable over-current protection device is disclosed in R.O.C. Patent Application No. 090104009 filed by the applicant on 22 Feb. 2001 and entitled “Electrode Structure of a Surface Mount Resettable Over-current Protection Device and Method of Manufacturing the Structure.” The method of the ROC Application comprises a step of providing conductive metal foils on the top and bottom surfaces of a PPTC material, a step of etching undesired metal foils on the top and bottom surfaces in the process of etching a PCB to form trenches, forming a main device substrate to be used as a surface mount resettable over-current protection device, coating a main structure of the main device substrate with insulating layers in a screening process, cutting the substrate into a plurality of strip-shaped substrates, forming a plurality of laminated substrate by the strip-shaped substrates, forming end-electrode bottom foil conductors, forming a soldering interface in an electrical plating process so as to finish end-electrode metal structures, and cutting the end-electrode metal structures into dice so as to finish the protection device.
However, the above method cannot reduce the size of the protection device because the end-electrode structures are formed by plating the stropped substrates, which greatly increases the cost of production.